The present invention relates to plasma display panels (PDPs) and more particularly to a dynamic color temperature and color deviation calibration method for improving image quality shown on PDP.
A manufacturing process of a conventional alternating current discharge type plasma display panel (PDP) 10 is shown in FIG. 1. First, two different activation layers are formed on glass substrates 11 and 12 respectively. Then seal the peripheries of the glass substrates together. A mixed gas consisting of helium (He), neon (Ne), and xenon (Xe) (or argon (Ar)) having a predetermined mixing volume ratio is stored in a discharge space formed in between the glass substrates. A front plate 11 is defined as one that facing viewers. A plurality of parallel spaced transparent electrodes 111, a plurality of parallel spaced bus electrodes 112, a dielectric layer 113, and a protective layer 114 are formed from the front plate 11 inwardly. From a corresponding rear plate 12 inwardly, a plurality of parallel spaced data electrodes 121, a dielectric layer 124, a plurality of parallel spaced ribs 122, and a uniform phosphor layer 123 are formed. When a voltage is applied on electrodes 111, 112, and 121, dielectric layers 113 and 124 will discharge in discharge cell 13 formed by adjacent spaced ribs 122. As a result, a ray having a desired color is emitted from phosphor layer 123.
The emissivity of a phosphor layer 123 is varied as panel temperature or operating frequency of PDP changes. Accordingly, as referring to FIGS. 2, 3 and 4 color temperature change and color deviation are occurred on panel of PDP 10, resulting in a poor image quality shown on panel. Above operating frequency is defined as discharge number per unit time occurred on a discharge cell 13. The higher the discharge number the higher the operating frequency will be. As shown in FIG. 2, the higher the operating frequency the lower the emissivity of phosphor layer 123 will be. This condition is even worse in a green phosphor layer 123. Hence, undesired color temperature change and color deviation are occurred on the conventional PDP as panel temperature and operating frequency increase. This in turn renders an unacceptable image quality.
It is thus an object of the present invention to provide a dynamic calibration method implemented on a plasma display panel (PDP), the method comprising the steps of: (a) utilizing laws of color matching for calculating an emissivity change of a pixel of the PDP in response to a brightness change of one of red, green, and blue lights emitted by a corresponding one of red, green and blue discharge cells of the PDP through a numeric operation; (b) dynamically adjusting brightness of one of the emitted red, green, and blue lights by increasing or decreasing strength of input video signal of each of the discharge cells; and (c) eliminating a color temperature and a color deviation of the PDP due to an emissivity change. The invention can render an image having an optimum color purity and color temperature by eliminating adverse effects on PDP due to emissivity change.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.